1. Field of the Invention
The present invention relates to a magnetic recording medium, particularly a magnetic recording medium excellent in the corrosion resistance and the abrasion resistance, and a method for its production.
2. Discussion of Background
Heretofore, in the field of magnetic disks as one field of memory disks, a Co type thin film magnetic recording layer has been provided in an attempt for high densification of a small-size Winchester type magnetic disk of 51/4 inch or less. For example, Co-P, Co-Ni-P, Co-Ni-Cr, Co-Cr, Co-Pt, Co-Cr-Pt, Co-Ni, Co-Ni-Pt, Co-Cr-Ni and Co-Cr-Ni Pt may be mentioned as representatives. Other than these, alloys using Sm, Re or rare earth elements, or those having various elements incorporated to such compositions to improve the magnetic properties, have been reported.
These thin film magnetic recording layers are thin metal films and accordingly have a problem that they are likely to be corroded by moisture, oxygen or carbon dioxide in air, whereby the magnetic recording properties tend to deteriorate. This tendency is particularly remarkable under high humidity conditions or under moisture condensation conditions.
To prevent such a problem, it has been in practice to provide at least one protective layer on the surface of the recording layer so that the recording layer will not be exposed directly to atmosphere. As such a protective layer, a carbon-type film is mainly used. However, an oxide film such as SiO.sub.2 or TiO.sub.2, has also been proposed.